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Two strip tillage systems for sweet corn production were compared to conventional tillage systems in western Oregon. A power take-off rotary tiller configured to till six rows per pass was used in 1997 and 1998; a shank/coulter strip tillage machine was used in 1999 and 2000. A paired t test experimental design was used in field-scale, on-farm research with eight replications in 1997-98 and 12 replications in 1999-2000. Sweet corn was harvested using the participating growers' corn pickers and yield was determined. A subset of the participating growers recorded types of machinery and labor for tillage operations and total costs were computed for each tillage system. The rotary strip tillage system produced 900 kg·ha-1 greater corn yields (P = 0.11) than conventional tillage. The shank/coulter strip tillage system produced yields comparable to conventional tillage (P = 0.95). The rotary strip tillage system reduced total tillage costs by an average of $38.50/ha compared to conventional tillage (P = 0.03) and reduced machinery operating time by 0.59 h·ha-1 (P = 0.01). The shank/coulter strip tillage system reduced tillage costs by $36.50/ha compared to conventional tillage (P = 0.003) and reduced machinery operating time by 0.47 h·ha-1(P = 0.001). Slugs damaged corn in several strip tillage fields requiring the use of slug bait to prevent economic damage. Herbicides used in conventional tillage systems were generally effective in the strip tillage systems. Mechanical cultivation with standard cultivating equipment was more difficult in some of the strip tillage fields with heavy cover crop residue.
A participatory, on-farm research project was initiated in 1992 in an effort to enhance mutual learning, knowledge, and experience of integrating cover crops into western Oregon vegetable production systems. A major goal of the project was to include growers, agribusiness representatives, governmental agency, Extension and university researchers in a collaborative learning process, emphasizing grower participation in the design and implementation of on-farm research and demonstration projects. To facilitate this participation from the planning stage forward, four “focus sessions” were hosted by lead farmers in different areas of the Willamette Valley to define growers' needs and interests relating to on-farm research and demonstration trials.
Based on individual growers' specific experimental objectives, cover crop evaluation trials were established on ten farms. Typically on each farm, 5 to 10 cover crop species or mixtures (grain and legume) were planted in large plot strips. Twenty five different cover crop species, varieties, and mixtures were planted. Seasonal cover crop biomass and nitrogen accumulation rates were determined, with cover crop impacts on crop yields and economic returns evaluated at selected sites.